Burner



United States Patent 15cc 3,531,229 BURNER Lars Goran Gobriel Berglund,Enkoping, Sweden, as-

signor to Aktiebolaget Bahco, Stockholm, Sweden, a joint-stock companyof Sweden Filed Apr. 17, 1969, SenNo. 817,021 Claims priority,application Sweden, Apr. 18, 1968,

,203/ 68 Int. Cl. F23q 7/08 US. Cl. 431-262 Claims ABSTRACT OF THEDISCLOSURE The present invention relates to a burner having a combustionchamber, a fuel atomizing or vapourizing body arranged in said chamberand consisting of a heat-resistant, porous material, means for supplyingliquid fuel to the combustion chamber and an electric igniting meansadapted to heat, vapourize and ignite the fuel, to initiate thecombustion sequence.

There exists in known constructions of carburation burners of the typespecified, particularly heaters fired o with petrol or diesel oil forinstance and installed in motor vehicles or water going vessels, aproblem which has not been satisfactorily solved; this problem being oneof positive functioning in heating, vapourizing and igniting theincoming fuel when starting the heater, and of maintaining the extent ofvapourization during operation in a manner which ensures uniformcombustion. A stable flame is to be desired, especially in the case ofcar heaters, partly from the aspect of noise and partly in view of thefact that a complete combustion must be obtained in all situations, sothat the heater can be accepted for maintaining the temperature of orheating the vehicle within confined spaces, such as a garage, in whichthe exhaust gases are discharged direct to the ambient air. The burnermust be capable of starting and working under widely varying conditions,which is particularly true when used in a vehicle heater. Hard winds andslip stream change the pressure conditions and thus the flow of air andfuel for combustion through the heater; shaking of the vehicle whilst inmotion and different attitudes of inclination when stationary varies thefuel supply conditions, while the condition of the electrical system canaffect the ignition sequence. Furthermore, the sudden supply of verycold air of combustion to the combustion chamber immediately afterstarting can cause local drops in temperature, which jeopardizes aneffective atomization of the fuel and delays the transition to acontinuous, stable combustion sequence.

The object of the invention is to provide a combustion chamber unitwhich is adapted to cooperate with the electric ignition means and toafford the advantages whereby fuel is absorbed and stored therein,thereby to equalize fluctuations in the supply of fuel; whereby the fuelis distributed over a wide area to facilitate vapourization; whereby alarge quantity of heat is stored through a relatively large mass,thereby obtaining a stabilizing heat inertia; whereby local heating isprovided for initiating vapourization and combustion of the fuel;whereby good 3,531,229 Patented Sept. 29, 1970 heat conductivity isobtained, to provide the vapourization and combustion zones with anopportunity of increasing possibility during the starting sequenceimmediately after ignition; and whereby a good flame maintainingfunction is afforded. All these properties, which facilitate ignition,stabilize combustion and render the burner less sensitive to variationsin external conditions, are obtained by means of a burner constructed inaccordance with the present invention, which is mainly characterized inthat the fuel vapourizing body is made of sintered, corrosion resistantsteel or other sintered material having a corresponding degree or higherdegree of heat conductivity; is adapted as the sole fuel accumulatingand fuel distributing means present in the combustion chamber; has thefuel supply means connected direct to the material thereof, to absorbthe fuel in the pores thereof; is adapted together with an auxiliarychamber and a main chamber, to maintain a stable flame, said auxiliarychamber and main chamber communicating through a constricted connectionand form together therewith a through-flow passage passing through thefuel vapourizing body and opening out at one end into the combustionchamber; and wherein the fuel vapourizing body is so arranged in thecombustion chamber that the air for combustion can be supplied throughthe through-flow passage and at the combustion chamber in such a waythat it contacts the tubular outersurface of the fuel vapourization bodyencircling the through-flow passage, and that the igniter means isarranged in connection with the auxiliary chamber.

The invention will now be described with reference to an embodimentthereof illustrated in the accompanying drawing, FIG. 1 of which showsin longitudinal section a burner fired by means of a spark plug, andFIG. 2 is a section taken along line 2--2 of FIG. 1.

In FIG. 1 there is shown a combustion chamber 2 arranged within a casing1, which also partly constitutes a wall portion of a heat-exchangearrangement situated between the gases of combustion and a flow of airor water. The combustion chamber 2 comprises a substantiallycylindrical, sheet-metal jacket 3, which may comprise one or more partsand which for heat insulation purposes is situated remote from the wallsurfaces of the casing 1. One end of the combustion chamber projects outfrom the interior of the casing 1 towards an end wall of said casing inwhich a spark plug 5 is arranged, while its other end opens out inwardlytowards the casing, to furnish an outlet for the gases of combustion viasaid end and an exhaust pipe (not shown). The requisite air forcombustion is supplied through an opening 6 leading to the interior ofthe casing within a section which is shielded against the portionthrough passed by the gases of combustion by a wall 7. Primary air ispassed to the burner through openings 8 disposed in the wall of atubular end portion of the combustion chamber jacket 3 located nearestthe end wall and embracing the spark plug 5, while secondary air issupplied through openings 9 in the form of gills disposed in a wallsituated in a radial plane, said wall connecting the main portion of thejacket 3 with said narrower end portion. The secondary air openings areadapted so as to impart a rotary movement to the air. The embodimentheretofor described coincides essentially with a conventional, e.g.gasoline, carburation burner.

In accordance with the invention, however, the combustion chamber 2 isprovided adjacent the spark plug 5 with a fuel vaporizing body 10 madeof sintered, heat resistant material of high thermal conductivity,preferably sintered corrosion resistant steel. The fuel vaporizing bodycomprises an essentially cylindrical body which is arranged coaxial withthe combustion chamber jacket 3 and which presents at its end facing thespark plug 5 an auxiliary chamber 14, while at its other end it presentsa main chamber 15 open towards the combustion chamber 2. The

3 auxiliary and main chamber are separated by a partition 16, which isprovided with one or more openings 17 (see FIG. 2) disposedasymmetrically relative to the vapourization space, to impart a swirlingmotion to the flow of air and gas for combustion. The spark plug hasonly one electrode, and this projects into the auxiliary chamber 14, toleave an appropriate sparking gap between that and the partition 16,which comprises the other pole of the ignition means. Fuel is suppliedvia a fuel supply line 18 connected to the fuel vapourizing body andopening out into a cavity or recess 19 in the material thereof, todistribute the fuel through the channels of the porous sinteredmaterial.

When starting the burner, pulses of high-voltage current are appliedthereto, to form sparks between the two poles, which comprise theelectrode of plug 5 and the partition 16, simultaneously as fuel ispassed to the recess 19. The high temperature of the spark causes a verylocal vapourization and ignition of the fuel, and thereby initiates acombustion process, the heat of which is used to increase progressivelythe combustion zone until the entire free surface of the fuelvapourizing body 10 is utilized for vapourizing the fuel and to providea stable flame.

The main chamber primarily serves during operation to mix preatomizedfuel and air, and to maintain and partially from the flame, although theannular space, through which the secondary air is passed, between theoutside of the vapourizing body and the wall of the combustion chamber 3also cooperates in this respect, at least with respect to mixing thefuel and air, as does also the auxiliary chamber 14. It is also possiblewithin the purview of the invention, to construct the burner in a way soas to present a number of main chambers arranged in parallel with regardto flow, whereby the relationship between free vapourization surface andthrough flow cross-section can be increased.

It is not necessary that ignition is caused by means of a sparking plugin order to practice the invention. For instance, a glow member arrangedto project into the auxiliary chamber can be used instead. Furthermore,the material of the fuel vapourization body 10 can be heated to atemperature sufiicient to vapourize and ignite the fuel resistively orinductively, by incorporating a resistance material in the material ofthe body, by using the material of the body itself as a resistance, orby arranging induction coils in or outside the body 10.

Irrespective of the type of ignition used, the fuel vapour izing bodyserves to facilitate ignition and during continuous operation assures astable combustion sequence in the manner specified in defining theobject of the (2), a fuel vapourizing body (10) arranged therein andmade of porous, heat-resistant material, means (18) for Supplying liquidfuel to the combustion chamber, and an electric igniting means (5)adapted to heat, vapourize and ignite the fuel, to initiate thecombustion sequence, characterized in that the fuel vapourizing body(10) is made of sintered material having a corresponding degree orhigher degree of heat conductivity; is adapted as the sole fuelaccumulating and fuel distributing means present in the combustionchamber; has the fuel supply means (18) connected direct to the materialthereof, to absorb the fuel in the pores thereof; is adapted togetherwith an auxiliary chamber (14) and a main chamber (15), to maintain astable flame, said auxiliary chamber and main chamber communicatingthrough a constricted connection (17) and form together therewith athrough-flow passage (14, 17, 15) passing through the fuel vapourizingbody (10) and opening out at one end into the combustion chamber (2);and wherein the fuel vapourizing body (10) is so arranged in thecombustion chamber so that air for combustion is supplied through thethrough-flow passage (14, 17, 15) and at the combustion chamber in sucha way that it contacts the tubular outer-surface of the fuelvapourization body encircling the through-flow passage, and that theigniter means (5) is arranged in connection with the auxiliary chamber(14).

2. The burner of claim 1, characterized in that the igniter means (5)comprises a glow body projecting into the auxiliary chamber 14).

3. The burner of claim 1, characterized in that the igniter means (5)comprises a sparking plug cooperating with the material of the fuelvapourization body (10) and arranged in or in the 'vicinity of theauxiliary chamber (14), said plug preferably being so arranged that thematerial of the fuel vapourizing body constitutes one spark pole.

4. The burner of claim 1, characterized in that the igniting means (5)comprises means for resistively or inductively heating a portion of thefuel vapourization body (10), at least adjacent the auxiliary chamber(14).

5. The burner of claim 1, characterized in that the connection (17)between the auxiliary chamber (14) and the main chamber (15) iscomprised of a symmetrically arranged openings in a wall (16) separatingthe chambers.

References Cited UNITED STATES PATENTS 2,229,717 2/1970 Brace et al.43l262 CARROLL B. DORITY, JR., Primary Examiner US. Cl. X.R.

